Do you find your mind wandering when you pray? 
Do you feel unsettled? 
Then you are in good company! 
Here is what the Saints have to say.

As St. Thérèse of Lisieux stated, “I have many distractions, but as soon as I am aware of them, I pray for those people, the thought of whom is diverting my attention. In this way, they reap the benefit of my distractions.” Talking to Him in a very loving and comfortable way, just as we would with any other friend or loved one, can be a helpful means of overcoming distractions.

 
“The Devil is never busier trying to distract us than when he sees us praying and asking God for grace. And why? Because the enemy sees that at no other time do we gain so many treasures of heavenly goods as when we pray.” — St. Alphonsus Liguori

 
St. Teresa of Avila suggests that, at the beginning of prayer, we close our eyes “in order to open wider the eyes of the soul,” thereby lessening the chance of distractions
She also says very simply: “Don't think a lot, love a lot!”

 
After you have made a decision that is pleasing to God, the Devil may try to make you have second thoughts. Intensify your prayer time, meditation, and good deeds. For if Satan's temptations merely cause you to increase your efforts to grow in holiness, he'll have an incentive to leave you alone.
St. Ignatius of Loyola
 

When you have distractions, don’t distract yourself still more by stopping to consider the why and the wherefore. --St. Padre Pio of Pietrelcina